1. Field of the Invention
The present invention relates to a binding device, and more particularly to a binding device in which a binding band wound around bound articles can be tightened and then cut.
2. Description of the Prior Art
A binding band 1 shown in FIG. 10 is known as a binding band which is used for binding wire articles such as wire harnesses or other bound articles. The binding band 1 is configured by an integral molded product which is made of a synthetic resin, and in which a head portion 13 is continuously integrated with one end of a band portion 12. A locking protrusion (not shown) is formed on one face of the band portion 12. By contrast, a band insertion hole portion 15 having an engagement pawl 14 is formed in the head portion 13. When, while bending the band portion 12, the other end of the band portion is inserted into the band insertion hole portion 15 from one side as indicated by the arrow a and then pulled out to the other side as indicated by the arrow b, the engagement pawl 14 is engaged in an arbitrary place of the band portion 12 with the locking protrusion, whereby the band portion 12 is inhibited from being pulled back from the band insertion hole portion 15 in the counter insertion direction (the direction counter to the direction of the arrow a). By contrast, when the band portion 12 is operated so as to be pulled out in the direction of the arrow b, the band portion 12 is inserted into the band insertion hole portion 15.
On the other hand, a binding device shown in FIGS. 8 and 9 is known as a device for binding bound articles such as wire harnesses with using the above-mentioned binding band 1 having the band portion 12 and the head portion 13 which comprises the band insertion hole portion 15 that allows the band portion 12 to be inserted thereinto in the direction of the arrow a, and that disables the band portion from being pulled out in the counter insertion direction (the direction counter to the direction of the arrow a).
FIG. 8 is a diagram of main portions showing a use state of the binding device 2, and FIG. 9 is a schematic section view of main portions of the binding device 2.
As shown in FIG. 8 or 9, the binding device 2 is formed into a gun-like shape having a barrel portion 21. A mouthpiece 3 is attached to the tip end of the barrel portion 21. A clamp 4 is placed behind the mouthpiece 3, and a cutting blade 5 is incorporated into the rear side of the mouthpiece 3. The mouthpiece 3 has a slit-like opening 31. The clamp 4 has a stationary piece 41, and a movable piece 42 which is swingable to approach and separate from the stationary piece 41. In the binding device 2, the clamp 4 is retracted by an operation of pulling-in a trigger which is not shown, and is advanced by an operation of returning the trigger to the original position. When the clamp 4 is retracted, the movable piece 42 swings with using a support shaft 43 as the fulcrum in a direction toward the stationary piece 41 to set a clamp mode, and, when the clamp 4 is advanced, the movable piece 42 swings with using the support shaft 43 as the fulcrum in a direction opposite to the stationary piece 41 to set an un-clamp mode. When a situation in which a force required for retracting the clamp 4 is larger than a threshold value occurs, a lever 51 shown in FIG. 9 operates to push up the cutting blade 5, so that the cutting blade 5 is moved to cross the opening 31 of the mouthpiece 3.
As shown in FIG. 8, the band portion 12 of the binding band 1 is wound around bound articles M such as wire harnesses, and then inserted into the band insertion hole portion 15 of the head portion 13. The band portion 12 which is pulled out to the other side of the band insertion hole portion 15 is passed through the opening 31 of the mouthpiece 3, and further passed between the stationary piece 41 and the movable piece 42 of the clamp 4. In the binding device 2, thereafter, the operations of pulling-in and returning the trigger are repeatedly performed. As a result, under the state where the head portion 13 of the binding band 1 is received by a receiving face 32 formed by a flat front end face of the mouthpiece 3, the band portion 12 is pulled out rearward by the clamp 4 from the band insertion hole portion 15 of the head portion 13 each time when the operation of pulling-in the trigger is performed, whereby the bound articles M are tightened by the band portion 12 (the tightening function of the binding device).
FIG. 11A illustratively shows the state where the bound articles M are tightened by the band portion 12 in this way, and FIG. 11B illustratively shows the state where the band portion 12 is cut.
In the operation of pulling-in the trigger after the bound articles M are tightened as shown in FIG. 11A, the force required for retracting the clamp 4 as indicated by the arrow d in FIG. 11B exceeds the threshold value, and therefore the cutting blade 5 is pushed up as indicated by the arrow c in FIG. 11B by the operation of the lever 51 shown in FIG. 9, and crosses the opening 31 of the mouthpiece 3. As a result, the cutting blade 5 cuts the band portion 12 to remove away an extra part 12a of the band portion 12 (the cutting away function of the binding device).
In the conventional binding device 2, the cutting blade 5 shown in FIG. 9 has a linear blade edge 52 (hereinafter, the linear blade edge 52 is referred to as “linear blade”). When the bound articles M are bound by the binding band 1 with using the binding device 2 as shown in FIG. 11B and the band portion 12 is cut to remove away the extra part 12a, therefore, also a cut end 12b of the band portion 12 protruding from the head portion 13 has a linear shape, and an edge is formed in each of the sides of the cut end 12b as shown in FIG. 12A.
When an edge is formed in each of the sides of the cut end 12b of the band portion 12 protruding from the head portion 13 as shown in FIG. 12A, there is the possibility that the hand or a finger of the worker is caught by the edge and the worker is injured.
In order to eliminate such a danger, it is required to form the cut end of the band portion 12 protruding from the head portion 13, into an arcuate shape. To comply with this requirement, the shape of the blade edge 52 of the cutting blade 5 is changed to an arcuate one as shown in FIG. 13.
FIG. 13 is a diagram showing a cross sectional shape of the mouthpiece 3 in which a cutting blade 5 having an arcuate blade edge 52 is incorporated into the rear side. The shape of the blade edge 52 of the cutting blade 5 in the figure is arcuate so that a place which is nearer to the center portion in the width direction or the widthwise center portion is positioned more backward. In other words, the blade edge 52 of the cutting blade 5 is formed into an arcuate shape which is positioned in the front side in the pulling-out direction (the arrow b) of the band portion 12 from the band insertion hole portion 15 of the head portion 13 of the binding band 1 shown in FIG. 10 (hereinafter, the arcuate blade edge 52 is referred to as “arcuate blade”).
In the case where the blade edge 52 of the cutting blade 5 is changed from a linear blade to an arcuate blade as described above, when the bound articles M are bound by the binding band 1 with using the conventional binding device 2 and the band portion 12 is cut to remove away the extra part 12a as shown in FIG. 11B, also the cut end 12b of the band portion 12 protruding from the head portion 13 has an arcuate shape, and an edge is not formed in the sides of the cut end 12b as shown in FIG. 12B, so that the above-mentioned danger is eliminated.
In the conventional binding device, as described with reference to FIG. 8, the head portion 13 of the binding band 1 is received by the receiving face 32 formed by the flat front end face of the mouthpiece 3. When the blade edge 52 of the cutting blade 5 is changed to an arcuate blade such as shown in FIG. 13, therefore, another problem which will be described with reference to FIG. 14 or 15 is produced. FIG. 14 is a diagram showing a cross sectional shape of the mouthpiece 3 in the state where the binding band 1 is placed in a normal position, and FIG. 15 is a diagram showing a cross sectional shape of the mouthpiece 3 in the state where the binding band 1 is not placed in the normal position.
In the state where the head portion 13 of the binding band 1 is received by the widthwise center portion of the flat receiving face 32 of the tip end of the mouthpiece 3, as shown in FIG. 14, the band portion 12 which protrudes from the head portion 13 to be passed through the opening 31 of the mouthpiece 3 is opposed to the widthwise center portion of the blade edge 52 configured by the arcuate blade of the cutting blade 5. When the band portion 12 is cut by the cutting blade 5, therefore, the cut end 12b (see FIG. 12) of the band portion 12 is formed into an arcuate shape which is bilaterally symmetrical. However, the formation of the cut end 12b (see FIG. 12) of the band portion 12 into a bilaterally symmetrical arcuate shape is performed only when the head portion 13 of the binding band 1 is received by the widthwise center portion of the flat receiving face 32 of the mouthpiece 3. In another state, the cut end 12b (see FIG. 12) of the band portion 12 is not formed into a bilaterally symmetrical arcuate shape. In the state where the head portion 13 of the binding band 1 is received by a place which is deviated from the center portion of the flat receiving face 32 of the mouthpiece 3 toward one side as shown in FIG. 15, for example, the band portion 12 which protrudes from the head portion 13 to be passed through the opening 31 of the mouthpiece 3 is opposed to the place which is deviated toward one side from the widthwise center portion of the blade edge 52 of an arcuate blade in the cutting blade 5. When the band portion 12 is cut by the cutting blade 5, therefore, the cut end 12b (see FIG. 12) of the band portion 12 is formed into a shape which is bilaterally asymmetrical, and an edge may be produced in one side of the cut end 12b. Occasionally, a situation may be caused in which only a part of the band portion 12 is cut by the cutting blade 5 and an uncut part remains in the other part of the band portion 12, so that the band portion 12 is not cut off. In FIGS. 14 and 15, L1 indicates the central axis which passes through the widthwise center portion of the receiving face 32 of the mouthpiece 3, and that of the arcuate blade of the cutting blade 5, and which elongates in parallel with the pulling-out direction, and L2 indicates the central axis which passes through the widthwise center portion of the band portion 12 of the binding band 1. In the case of FIG. 14, the two axes L1 and L2 coincide with each other.
As described above, in the conventional binding device, since the blade edge 52 of the cutting blade 5 is a linear blade, the cut end 12b of the band portion 12 of the binding band 1 which binds the bound articles M has a linear shape, and there is the danger that the worker is injured by edges formed in the sides of the cut end 12b. 
When the blade edge 52 of the cutting blade 5 is changed to an arcuate blade in order to eliminate such a danger, a manual cumbersome work of positioning the head portion 13 of the binding band 1 to the widthwise center portion of the receiving face 32 of the mouthpiece 3 to be received thereby must be conducted because the receiving face 32 of the mouthpiece 3 is formed as a flat face. Consequently, there is a problem in that the efficiency of a binding work in which binding must be performed in many places is largely lowered.